Hearing aids often comprise a connector with a set of closely spaced electrical terminals operatively connected to one or more internal hearing aid components. Such connectors normally form part of the housing of the hearing aid and may be located at the outer surface or at least near the outer surface thereof. This location enables an external device to be connected to the hearing aid. As a result an external device may be operatively connected to the hearing aid via the connector of the hearing aid; e.g. using a cable including a plug adapted to engage with the connector.
In some hearing aids the terminals may form an electrical programming interface for an external computer or programming device or the terminals may form part of such an interface. Therefore prior to programming a programmable hearing aid, the external programming device to be used may be electrically connected to the hearing aid via the connector. Hereby an external programming device may be operationally connected to one or more internal components of the hearing aid, such as a processor and/or a memory device, and the hearing aid may be programmed, if desired.
In order to program a hearing aid the connector includes at least one electrical terminal adapted to form a data communication path between the external device and one or more internal components of the hearing aid during programming. The hearing aid may be supplied with setting data from the external programming device connected thereto, or the hearing aid may exchange data with the programming device.
Normally, the connector in a hearing aid comprises two or more electrical terminals which are connected to internal hearing aid components. For example, the set of electrical terminals of the connector may include one or more electrical power terminals and one or more terminals for data communication.
The type of hearing aid initially mentioned also includes other types of hearing aids than programmable hearing aids having a programming interface. For example, the terminals may form an external audio interface adapted to receive audio signals from e.g. a miniature FM receiver or other audio sources.
A hearing aid of the above-mentioned type may include detecting means adapted to determine whether an external device is connected to the hearing aid or not. Hereby, the hearing aid may for example be operated in different modes depending on whether an external device is connected to the hearing aid or not. For example, a programming hearing aid may be brought into a programming mode when the external programming device is connected thereto. Likewise, the hearing aid may again be brought into a predetermined mode of operation, e.g. a mode of normal operation, when an external device, such as a programming device, is no longer operationally connected to the hearing aid. During programming mode, the hearing aid may for example receive programming data specifying the signal processing to be performed during one or more modes of operation.
The patent publication U.S. Pat. No. 5,404,407 discloses a programmable hearing aid unit including electrical contacts for connecting a programming circuit of the hearing aid to an external programming unit via a programming socket at the housing.
Further, the German utility model publication DE 299 15 874 is an example of a programmable hearing aid having an electrical programming interface.
The terminals of a connector in a hearing aid are normally closely spaced as the terminals hereby may form part of a connector or socket as mentioned above. This is desirable as an interface having two or more closely spaced terminals enables the connection and disconnection of an external device to be performed easily, quickly and in a fail-safe manner. Furthermore, as hearing aids are unobtrusive, they are most often given miniature dimensions. Therefore, only a small amount of surface space is available for interfaces and the like on the surface of the hearing aid housing and the terminals must be closely spaced.
The drawback of placing the electrical terminals at or near the outer surface of the hearing aid has been found to be that the electrical terminals are unprotected from the external environment and as a result they are often subjected to corrosion. This is undesirable as corrosion makes connection to external devices unreliable and may at worst break the connection.